The prior art with which my invention is concerned is exemplified in U.S. Pat. Nos. 2,871,831, issued Feb. 3, 1959, to one P. C. Patin, for INTERNAL GEAR MACHINES; 3,391,608 issued July 9, 1968, to M. J. Huber, for HYDRAULIC TORQUE MOTOR; and U.S. Pat. No. 3,490,383, issued Jan. 20, 1970, to J. T. Parrett for HYDRAULIC PUMP OR MOTOR.
Each of these patents deals with various and sundry aspects of orbital type devices which may be used as hydraulic pumps or motors. The Patin patent, for example, illustrates a form of characterized or specially configured porting for use with an orbiting inner member of a gerotor set and illustrates ports of a triangular shape which are defined by circular arcs that are related to the shape of the teeth on the inner externally toothed, orbiting member. The Huber patent refers to recessed portions adjacent the roots of the internal teeth on an outer member of a gerotor set which is designed to orbit about an externally toothed inner member. These are described as being notches to prevent trapping of fluid during relative movement of the gerotor elements. The Parrett patent illustrates a deep root tooth configuration for the outer member of a gerotor set which is also designed to move in an orbital manner with respect to the inner externally toothed member of the gerotor set. The purpose of the roots in the Parrett patent is to provide access or fluid communication with a number of circumferentially spaced fluid ports which are disposed a substantial radial distance from the axis of rotation of the rotary member of the gerotor set. Without the deep rooted construction, it would be impossible to place the ports in the position desired by the inventor with the general form of gerotor set construction as exemplified in the Huber and Patin patents.